Method and apparatus for sensing armature position in direct current solenoid actuators
AssigneeHUSCO International, Inc.
InventorLong-Jang Li
Life of this patent
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Abstract
An apparatus detects a position of an armature within a solenoid coil by superimposing a fixed frequency sensing signal onto the coil driver signal. The combined signal is applied to the solenoid coil and an alternating current component varies with changes in inductance of the solenoid coil that result from position changes of the armature. A current sensor produces an output signal indicating a level of current flowing through the solenoid coil and a filter extracts the alternating component of that output signal that results from the sensing signal. A position circuit determines the position of the armature from an output from the filter.
Claims23
An apparatus for detecting a position of an armature within a coil of a solenoid actuator, the apparatus comprising:
- a first source of a driver signal having a current which is varied to move the armature into a plurality of positions;
- a second source of a position sensing signal having a given frequency;
- a device which combines the driver signal and the sensing signal to form a composite signal;
- a conductor for connecting the device to the coil;
- a current sensor which produces a sensor signal indicating a level of current flowing through the coil;
- a filter that passes a component of the sensor signal at the given frequency to produce a filter signal;
- and
- a position circuit connected to the filter and comprising an amplitude modulation detector and which processes the filter signal to produce a location signal indicating the position of the armature.
An apparatus for detecting a position of an armature within a coil of a solenoid actuator, the apparatus comprising:
- a first source of a driver signal having a first frequency and being pulse width modulated to move the armature into a plurality of positions within the coil;
- a second source of a sensing signal having a second frequency;
- a device which combines the driver signal and the sensing signal to form a composite signal;
- a conductor for connecting the device to the coil;
- a sensing circuit including a current sensor that produces an output signal indicating a level of current flowing through the coil, a band pass filter that passes a component of output signal which corresponds to the second frequency;
- and an amplitude detector connected to an output of the band pass filter;
- and
- a position circuit connected to the sensing circuit and determining the position of the armature within a coil of a solenoid actuator in response to a signal from the amplitude detector which corresponds to a current magnitude of the sensing signal.
A method for detecting a position of an armature within a coil of a solenoid actuator, the method comprising:
- producing a current regulating signal which is varied to move the armature into a plurality of positions;
- generating a sensing signal;
- combining the current regulating signal and the sensing signal to form a composite signal;
- applying the composite signal to the coil;
- detecting a magnitude of current flowing through the coil to produce a current signal;
- filtering the current signal to extract a component signal which results from the sensing signal;
- and
- amplitude demodulating the component signal to determine the position of the armature within the coil.
An apparatus for detecting a position of an armature within a coil of a solenoid actuator, the apparatus comprising:
- a first source of a pulse width modulated driver signal in which pulses have a width that varies to move the armature into a plurality of positions;
- a second source of a position sensing signal;
- a device which combines the driver signal and the sensing signal to form a composite signal;
- a conductor for connecting the device to the coil;
- a sensing circuit to measure a magnitude of current of the sensing signal which flows through the coil;
- and
- a position circuit connected to the sensing circuit and determining the position of the armature within a coil of a solenoid actuator from the magnitude of current of the sensing signal, the position circuit producing a location signal indicating that position of the armature.
Dependencies are inferred from the claim text.